The embodiments described herein relate generally to electrical machines, and more specifically, to a stator having a liner.
An electric machine is typically in the form of an electric generator or an electric motor. The machine typically has a centrally located shaft that rotates relative to the machine. Electrical energy applied to coils within the motor initiates this relative motion which transfers the power to the shaft and, alternatively, mechanical energy from the relative motion of the generator excites electrical energy into the coils. For expediency the machine will be described hereinafter as a motor. It should be appreciated that a motor may operate as a generator and vice versa.
A stationary assembly, also referred to as a stator, includes a stator core and coils or windings positioned around portions of the stator core. It is these coils to which energy is applied to initiate this relative motion which transfers the power to the shaft. These coils are formed by winding wire, typically copper, aluminum or a combination thereof, about a central core to form the winding or coil.
In an assembled configuration the coils are positioned in a spaced apart relationship about the stationary assembly that typically has a generally hollow cylindrical configuration with the coils positioned internally. The power of the electric motor is dependent on the amount of energy that may be applied to the coils and that amount of energy is proportional to the amount of wire that may be positioned about the stationary assembly. The amount of wire positioned about the stationary assembly is typically referred to as the slot fill. Placing as much wire in the coils as possible, also known as maximizing the slot fill is thus desirable,
Of many methods of manufacturing the stator and winding the wire to form the coil in particular, the following three methods are typical. The first is to form a rigid hollow cylindrical core with internal protrusions of teeth around which the coils are wound. The core is typically produced by stacking a plurality of rigid hollow laminations and joining them to form the rigid hollow cylindrical core. This method requires the wire to be fed around the teeth with a device called a needle. The need to provide for movement of the needle around the teeth limits the amount of wire that may be used to form the coil.
A second method is to similarly form a rigid hollow cylindrical core with internal protrusions of teeth and to provide spools or bobbins that may be removably secured to the teeth of the core. The coils are formed by winding wire around the coils while separated from the stator and then by assembling the wound bobbins onto the teeth of the stator. The separated coils provide improved access around the coil to more completely form the coil.
A third known method of manufacturing a stationary assembly includes stacking a plurality of laminations and rolling the stack to form a round stator. The laminations are stamped from a sheet of stock material and stacked to form a substantially linear array of stator sections and connecting members. The substantially linear array includes a first end and a second end. Teeth are formed along one side of the linear array. Windings may be wound on the stator sections around the teeth while the laminations are in the linear orientation in a configuration where the linear array of laminations are arched with the teeth positioned outwardly. Once the windings are positioned on the stator sections, the stack is formed into a second shape. To form the stack into the second shape, the stack is rolled around a central axis and the first end is coupled to the second end with the teeth positioned inwardly. The second shape is the substantially round shape of a stator. Typically, the second shape is maintained by securing the first end to the second end. The linear arrays provide improved access around the teeth to more completely form the coil.
Regardless of which method is used to form the stator, the coils need to be wrapped around the teeth of the stator core including the opposed ends of the stator core, which are typically the end laminations, The portions of the coils outside of the end laminations are typically called end turns. For the coils to provide the electromagnetic fields necessary to power the motor, the end turns need to be properly electrically interconnected, typically with the use of additional electrical wires (interpole connections and leads) and/or electrical connectors. Typically interpole connections need to be laced and lead ties secured to the motor. Typically end caps made of an insulating material, typically a polymer, are placed over the end laminations and are used to guide the additional electrical wires and/or electrical connectors. The end caps represent an additional cost to the motor, add to the length of the motor and limit the paths of the additional electrical wires resulting in complex and tortuous wire paths.
The present invention is directed to alleviate at least some of these problems with the prior art,